Quality control analysis of imported fertilizers used in Ghana: the ...

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28 Proceedings of the International Academy of Ecology and Environmental Sciences, 2012, 2(1):27-40 continent (Ackah et al., 2011; Sayyed and Wagh, 2011; Tiwari, 2011). However, history shows that no region in the world achieved food security and substantial productivity increases without significantly expanding fertilizer use (FAO, 2006; Zhang and Zhang, 2007). Africa’s soils are much depleted and poor compared to other continents and to produce on these soils, fertilizer is one of the major inputs that would be needed to replenish the soil (FAO, 2006). Replenishing soil fertility is important because soil nutrient is the number-one natural resource in Africa currently being depleted and the nutrient capital of African soils is being mined just like mineral deposits of metals or fossil fuels (FAO, 2006). Smaling (1993) estimates the depletion rates of soil nutrients as 22 Kg/ha/yr for nitrogen (N), 2.5 Kg/ha/yr for phosphorus (P) and 15 Kg/ha/yr for potassium (K) in Africa. The challenges facing agriculture in Ghana are immense, with the large increase in population over the past several few decades, there has been increased pressure on land, and farmers can no longer fallow their fields to regain fertility like they used to. From 1988 to 1990, fertilizer use in Ghana averaged about 11,000 nutrients tons. However the nutrient requirements for the various crops for the same period were estimated to be 90,000 nutrient tons (Mwangi, 1996). The implications for Ghana are clear: depletion of soil nutrients is becoming a serious constraint to soil fertility and crop productivity. Moreover, the level of depletion suggests that efficient and sustainable use of fertilizers would be required to maintain soil fertility (Mwangi, 1996). The Government of Ghana recognizes the critical role effective application of fertilizers is in increasing agricultural productivity and contributing to the achievement of national food security. Farmers throughout the country must therefore have access to good quality fertilizers at reasonable costs. The fertilizers should be appropriate for the local conditions, effective in use and according to the quality standards as per the label on the packaging. Ghana imports all of its fertilizers and in 2003, imported about 1.43×10 5 metric tons of fertilizer (FAO, 2005). These are mostly mineral or inorganic fertilizers that contain the macro nutrients required by plants. Personal communications revealed that some Ghanaian farmers have raised concerns about the quality of some of these imported fertilizers they use on their farms. Thus, hinting on the fact that some of the imported fertilizers used in Ghana are not meeting quality standards. At the moment, there is no quality control system in the country dedicated to checking the quality of fertilizers that come into the country. Even though some work have already been done on fertilizers in Ghana (Addo et al., 2006; Appiah et al., 2000; Ofori-Frimpong et al., 1997), the problem of establishing the quality criteria for imported fertilizers has not been dealt with and Ghana is yet to have a quality data base for fertilizers against which any proper quality control work could be done. There is therefore the need for a system to regulate the quality of fertilizers that come into the country to ensure that the fertilizers and crop protection chemicals offered to the farmers are fit for the purpose stated, complies with required specifications and that adequate guidance is given to the farmer on their safe and effective application. The fertility status of soils in the different regions of Ghana varies considerably due to the nature of soils that are found there (MOFA, 2003). The levels of organic carbon, nitrogen and available phosphorus are generally very low. Table 1 shows the average soil fertility status of some of the regions in Ghana. Figures are not given for the levels of potassium in table 1 since it is mostly abundant in the soils of Ghana (MOFA, 2003). According to the fertilizer society of South Africa, the primary macronutrients are usually lacking from the soil first because plants use large amounts for their growth and survival. The secondary macronutrients are usually enough in the soil so the use of fertilizers is not always required to introduce them into the soils. Sulphur for instance is usually found in sufficient amounts in the slow decomposition of soil organic matter, hence a good reason for not throwing away grass clippings and leaves (Vlek 1985). Calcium IAEES www.iaees.org
Proceedings of the International Academy of Ecology and Environmental Sciences, 2012, 2(1):27-40 29 and magnesium are however associated with lime fertilizers and automatically find their way into the soil when lime fertilizers are applied to treat acidic soils (Vlek, 1985). Table 1 Average soil fertility status of some regions in Ghana (MOFA, 2003) Region Organic Matter (%) Total Nitrogen (%) Available P (mg/kg soil) Available Ca (mg/kg soil) Ashanti 1.5 - 3.0 0.1 - 0.3 0.1 - 12.0 50 - 100 B-Ahafo 0.3 - 1.7 — 0.1 - 63.4 16 – 140 G. Accra 0.1 - 1.7 0.05 - 0.9 0.8 - 144.0 14 – 470 Northern 0.6 - 2.0 0.02 - 0.05 2.5 - 10.0 45 – 90 Upper East 1.1 - 2.5 0.06 - 0.14 1.8 - 14.8 44 – 152 Upper West 0.5 - 1.3 0.01 - 0.07 2.0 - 7.4 52 -152 Western 1.0 - 5.7 0.06 - 5.4 0.4 - 11.3 28 – 420 The major importers of inorganic fertilizers into Ghana are private companies (Gerner, 1995). Imported fertilizers can be classified as straight (containing one of the primary nutrients N, P and K), or compound (containing at least two of the three primary nutrients) (Bonsu et al., 1996). The imports of compound fertilizers far exceed the imports of the other fertilizers in Ghana (FAO 2005). Regardless of the name, however, fertilizers are labeled according to the relative amounts of each of these three primary macronutrients by weight (i.e., mass fraction). Thus an NPK 18−51−20 fertilizer grade contains, by weight, 18% elemental nitrogen (N), 22% elemental phosphorus (P), and 16% elemental potassium (K). Replenishing soil fertility with fertilizers does not just solve the problem. It is therefore important that, the right amount of nutrients are added to the soil since under application of nutrients may slow plant growth and excess fertilizer application may lead to situations such us fertilizer burns in crops resulting in a drying out of the roots and damage or even death of the plant, and further cause problems to the environment (Avoiding fertilizer burns 2010). 2 Materials and Method 2.1 Inclusion criteria for selecting companies for sampling Fertilizer samples were obtained from five fertilizer importing companies in Accra and Tema metropolises. The criteria for selecting a company for sampling were based on the company being an importer of fertilizer and a major stake holder in the Ghana fertilizer industry. Visual surveys of the companies warehouses were made to make sure the warehouses were accessible for the sampling procedure that was intended to be used in this research. Five companies were thus identified and selected for this research. The companies were given code names A, C, D, G and Y. 2.2 Sample collection Samples were collected under the authorisation from the Plant Protection and Regulatory Services Directorate (PPRSD) of the Ministry of Food and Agriculture (MOFA), the funding institution for this research. Standard procedures from the Guide to Laboratory Establishment for Plant Nutrient Analysis manual of the Food and Agriculture Organisation (FAO) (Motsara et al., 2008) was used in the sampling. The collection of a representative sample of a fertilizer was an important step in fertilizer analysis and quality control (Motsara et IAEES www.iaees.org
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